SUMMARY OF WORK: Epidemiological surveys have shown an increased incidence of mammary cancer in recent years, especially in Japan. This increased incidence is positively correlated with increased consumption of animal fat. Experimentally, dietary lipids, especially unsaturated fatty acids, have been shown to enhance the efficiency of carcinogen induced rat and mouse mammary tumors and to promote the growth of transplantable mammary tumors in mice. Our objective is to determine the mechanism by which the process occurs - either directly on mammary epithelial cells with lipids acting as initiators or promoters or as nutritional factors or, alternatively, whether lipids promote the process indirectly on mammary cells by influencing the hormonal status of the host. The approach is to evaluate the above alternatives by comparing the effects of lipids on normal rodent mammary epithelial cell growth and transformation as well as the nutritional requirements for growth of cultures derived from carcinogen induced tumors. BIBLIOGRAPHIC REFERENCES: Kidwell, W.R. and Mage, M.G. Changes in poly(ADP-ribose) and poly (ADP-ribose) polymerase in synchronous Hela cells. Biochem. 15: 1213-1217, 1976. Kidwell, W.R. Radioimmunoassay of poly(ADP-ribose) in extracts of growth-synchronized Hela cells. In Hilz, H. (Ed.): Proc. 4th Internat. Symp. on poly(ADP-ribose) and ADP-ribosylation of protein. Berlin, Walter de Gruyter, 1976, p.8.